:root {
    --primary: #3498db;
    --primary-dark: #2980b9;
    --secondary: #2c3e50;
    --success: #2ecc71;
    --warning: #f39c12;
    --danger: #e74c3c;
    --light: #ecf0f1;
    --dark: #34495e;
    --gray: #95a5a6;
    --white: #ffffff;
    --shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
  }
  
  * {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
  }
  
  body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background-color: #f8fafc;
    color: #333;
    line-height: 1.6;
  }
  
  h1, h2, h3 {
    color: var(--secondary);
    margin-bottom: 1rem;
  }
  
  header {
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    color: var(--white);
    padding: 1rem 0;
    box-shadow: var(--shadow);
  }
  
  footer {
    background: var(--secondary);
    color: var(--white);
    padding: 1rem 0;
    text-align: center;
  }
  
  .container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1rem;
  }
  
  /* 按钮样式 */
  .btn {
    display: inline-block;
    padding: 0.5rem 1rem;
    background: var(--primary);
    color: var(--white);
    border: none;
    border-radius: 4px;
    cursor: pointer;
    font-weight: 500;
    transition: background 0.3s;
  }
  
  .btn:hover {
    background: var(--primary-dark);
  }
  
  .btn:disabled {
    background: var(--gray);
    cursor: not-allowed;
  }
  
  /* 卡片样式 */
  .card {
    background: var(--white);
    border-radius: 8px;
    box-shadow: var(--shadow);
    padding: 1rem;
    margin-bottom: 1rem;
    transition: box-shadow 0.3s;
  }
  
  .card:hover {
    box-shadow: 0 6px 12px rgba(0, 0, 0, 0.15);
  }
  
  /* 图表容器 */
  .chart-container {
    background: var(--white);
    border-radius: 8px;
    box-shadow: var(--shadow);
    padding: 1rem;
    margin-bottom: 1rem;
    transition: all 0.3s;
  }
  
  .chart-container:hover {
    box-shadow: 0 6px 12px rgba(0, 0, 0, 0.15);
  }
  
  .chart-title {
    font-size: 1.2rem;
    font-weight: 600;
    text-align: center;
    margin-bottom: 1rem;
    color: var(--secondary);
  }
  
  /* 网格布局 */
  .grid {
    display: grid;
    gap: 1.5rem;
  }
  
  .grid-cols-1 {
    grid-template-columns: repeat(1, 1fr);
  }
  
  .grid-cols-2 {
    grid-template-columns: repeat(2, 1fr);
  }
  
  .grid-cols-3 {
    grid-template-columns: repeat(3, 1fr);
  }
  
  .grid-cols-4 {
    grid-template-columns: repeat(4, 1fr);
  }
  
  @media (min-width: 768px) {
    .md\:grid-cols-2 {
      grid-template-columns: repeat(2, 1fr);
    }
  }
  
  @media (min-width: 992px) {
    .lg\:grid-cols-2 {
      grid-template-columns: repeat(2, 1fr);
    }
    .lg\:grid-cols-3 {
      grid-template-columns: repeat(3, 1fr);
    }
    .lg\:grid-cols-4 {
      grid-template-columns: repeat(4, 1fr);
    }
  }